.htaccess RewriteRule not working on some links

This is driving me insane - I have certain links that are re-written on a site that work perfectly fine (and I am not new to re-wring urls) but have just found that some others aren't and I cannot fathom out why.

What is in $faq['slug']? By the way, why aren't you just using PHP to take care of the redirecting process? :) E.g.: redirect everything to index.php, then use $_SERVER['REQUEST_URI'] to find out what needs to be done.

E.g. www.yoursite.com/products/brand/diesel would redirect to index.php, which would then see that the URI is "products/brand/diesel", which information you could then use to PHP-include the appropriate files.